It would take the likes of a Carl Sagan to utter a number large enough to represent the amount of steam generated each day for industrial and other commercial purposes throughout the world. All this sounds heartening at first, until it is realized that a good part, if not all of this steam is generated in boilers or steam generators which create large volumes of air pollutants, particularly, carbon monoxide, unburnt hydrocarbons and nitrogen oxides. The generation of these pollutants and the existence of stringent air quality standards, especially with respect to the nitrogen oxides, have required operators of steam generators to take measures for cleansing these pollutants from their systems' exhaust. These measures often require quite costly and complicated machinery.
The taking of such post-combustion measures ignores the real source of the problem--the combustor. The normal combustor or furnace device operates at low static pressure (1 psig) and uses a relatively large chamber to maintain therein one or more ball-shaped flames in steady state condition. Because the flame is not allowed any significant degree of convection from one spatial location to another, thermal striations develop in the flame wherein there exists a high temperature central core surrounded by a cooler exterior envelope of combusting gas. The hot core most often exceeds the critical temperature required for the production of nitrogen oxides (approximately 2800.degree. F.). Also, the temperatures of the gases surrounding the core are too low for complete combustion. These peripheral cooler gases cause the flame to emit carbon monoxide and incompletely combusted hydrocarbons in addition to the nitrogen oxides generated at the hot core of the flame.
There is the downhole steam generator described in U.S. Pat. No. 4,243,098 to Meeks et al. which seems to depart from the usual design for steam generators, but which nonetheless exhibits the same shortcomings. In Meeks et al, a combustor comprising a combustion chamber and a single nozzle is used as a source of heated gas for purposes of generating steam at the base of a petroleum well hole. However, there is shown in FIG. 1 a single, elongated ball-flame and it is stated therein that the heated gases initially attain a temperature of approximately 3200.degree. F., a temperature well above the critical temperature where nitrogen oxides being forming.